Patent Literature (PTL) 1 describes an electronic device, such as a mobile phone terminal, in which a piezoelectric element attached to a main surface of a panel is deformed to vibrate the panel, to transmit human body vibration sound to an object in contact with the panel. In PTL 1, the human body vibration sound is defined as sound that is transmitted to the auditory nerve of a user in contact with a vibrating thing, through part of the user's body (e.g. the cartilage of the external ear).